﻿/*
* jQuery history plugin
* 
* sample page: http://www.mikage.to/jquery/jquery_history.html
*
* Copyright (c) 2006-2009 Taku Sano (Mikage Sawatari)
* Licensed under the MIT License:
*   http://www.opensource.org/licenses/mit-license.php
*
* Modified by Lincoln Cooper to add Safari support and only call the callback once during initialization
* for msie when no initial hash supplied.
*/


jQuery.extend({
    historyCurrentHash: undefined,
    historyCallback: undefined,
    historyIframeSrc: undefined,
    historyNeedIframe: jQuery.browser.msie && (jQuery.browser.version < 8 || document.documentMode < 8),

    historyInit: function(callback, src) {
        jQuery.historyCallback = callback;
        if (src) jQuery.historyIframeSrc = src;
        var current_hash = location.hash.replace(/\?.*$/, '');

        jQuery.historyCurrentHash = current_hash;
        if (jQuery.historyNeedIframe) {
            // To stop the callback firing twice during initilization if no hash present
            if (jQuery.historyCurrentHash == '') {
                jQuery.historyCurrentHash = '#';
            }

            // add hidden iframe for IE
            jQuery("body").prepend('<iframe id="jQuery_history" style="display: none;"' +
				' src="javascript:false;"></iframe>'
			);
            var ihistory = jQuery("#jQuery_history")[0];
            var iframe = ihistory.contentWindow.document;
            iframe.open();
            iframe.close();
            iframe.location.hash = current_hash;
        }
        else if (jQuery.browser.safari) {
            // etablish back/forward stacks
            jQuery.historyBackStack = [];
            jQuery.historyBackStack.length = history.length;
            jQuery.historyForwardStack = [];
            jQuery.lastHistoryLength = history.length;

            jQuery.isFirst = true;
        }
        if (current_hash)
            jQuery.historyCallback(current_hash.replace(/^#/, ''));
        setInterval(jQuery.historyCheck, 100);
    },

    historyAddHistory: function(hash) {
        // This makes the looping function do something
        jQuery.historyBackStack.push(hash);

        jQuery.historyForwardStack.length = 0; // clear forwardStack (true click occured)
        this.isFirst = true;
    },

    historyCheck: function() {
        if (jQuery.historyNeedIframe) {
            // On IE, check for location.hash of iframe
            var ihistory = jQuery("#jQuery_history")[0];
            var iframe = ihistory.contentDocument || ihistory.contentWindow.document;
            var current_hash = iframe.location.hash.replace(/\?.*$/, '');
            if (current_hash != jQuery.historyCurrentHash) {

                location.hash = current_hash;
                jQuery.historyCurrentHash = current_hash;
                jQuery.historyCallback(current_hash.replace(/^#/, ''));

            }
        } else if (jQuery.browser.safari) {
            if (jQuery.lastHistoryLength == history.length && jQuery.historyBackStack.length > jQuery.lastHistoryLength) {
                jQuery.historyBackStack.shift();
            }
            if (!jQuery.dontCheck) {
                var historyDelta = history.length - jQuery.historyBackStack.length;
                jQuery.lastHistoryLength = history.length;

                if (historyDelta) { // back or forward button has been pushed
                    jQuery.isFirst = false;
                    if (historyDelta < 0) { // back button has been pushed
                        // move items to forward stack
                        for (var i = 0; i < Math.abs(historyDelta); i++) jQuery.historyForwardStack.unshift(jQuery.historyBackStack.pop());
                    } else { // forward button has been pushed
                        // move items to back stack
                        for (var i = 0; i < historyDelta; i++) jQuery.historyBackStack.push(jQuery.historyForwardStack.shift());
                    }
                    var cachedHash = jQuery.historyBackStack[jQuery.historyBackStack.length - 1];
                    if (cachedHash != undefined) {
                        jQuery.historyCurrentHash = location.hash.replace(/\?.*$/, '');
                        jQuery.historyCallback(cachedHash);
                    }
                } else if (jQuery.historyBackStack[jQuery.historyBackStack.length - 1] == undefined && !jQuery.isFirst) {
                    // back button has been pushed to beginning and URL already pointed to hash (e.g. a bookmark)
                    // document.URL doesn't change in Safari
                    if (location.hash) {
                        var current_hash = location.hash;
                        jQuery.historyCallback(location.hash.replace(/^#/, ''));
                    } else {
                        var current_hash = '';
                        jQuery.historyCallback('');
                    }
                    jQuery.isFirst = true;
                }
            }
        } else {
            // otherwise, check for location.hash
            var current_hash = location.hash.replace(/\?.*$/, '');
            if (current_hash != jQuery.historyCurrentHash) {
                jQuery.historyCurrentHash = current_hash;
                jQuery.historyCallback(current_hash.replace(/^#/, ''));
            }
        }
    },
    historyLoad: function(hash) {
        var newhash;
        hash = decodeURIComponent(hash.replace(/\?.*$/, ''));

        if (jQuery.browser.safari) {
            newhash = hash;
        }
        else {
            newhash = '#' + hash;
            location.hash = newhash;
        }
        jQuery.historyCurrentHash = newhash;

        if (jQuery.historyNeedIframe) {
            var ihistory = jQuery("#jQuery_history")[0];
            var iframe = ihistory.contentWindow.document;
            iframe.open();
            iframe.close();
            iframe.location.hash = newhash;
            jQuery.lastHistoryLength = history.length;
            jQuery.historyCallback(hash);
        }
        else if (jQuery.browser.safari) {
            jQuery.dontCheck = true;
            // Manually keep track of the history values for Safari
            this.historyAddHistory(hash);

            // Wait a while before allowing checking so that Safari has time to update the "history" object
            // correctly (otherwise the check loop would detect a false change in hash).
            var fn = function() { jQuery.dontCheck = false; };
            window.setTimeout(fn, 200);
            jQuery.historyCallback(hash);
            // N.B. "location.hash=" must be the last line of code for Safari as execution stops afterwards.
            //      By explicitly using the "location.hash" command (instead of using a variable set to "location.hash") the
            //      URL in the browser and the "history" object are both updated correctly.
            location.hash = newhash;
        }
        else {
            jQuery.historyCallback(hash);
        }
    }
});


